The factory parts and designs on generic (as opposed to custom) market planes have to be compromised for cost and attachment reasons (just like on a Ford versus a Ferrari). An external flange is the least expensive design and the easiest to install; but it forces a different shape at the leading and trailing edges, puts uneven surfaces in the airstream, and takes up room that could be used instead for a more flowing design.

When the engineering group worked through the project to clean up drag on the Sierra, very few of their findings provided a benefit that outweighed the costs. This was bad news at the time, since the Sierra was already priced much higher than its 200HP retract competition. Only small changes, such as the reduced aileron under-wing skin gaps (as opposed to true gap seals), oval-section step supports, and the gascolator fairing, actually made it into production.

Here is a partial list of things that they tried, that I know of and can recall at the moment; there may have been more. I have photos of some of these, that I hope to get up on the BAC website someday:
1. Flushed filler necks and caps.
2. Flushed wingtip mountings.
3. Flushed taxi light lens mountings.
4. Full-coverage main gear strut and wheel doors.
5. Full-coverage nose gear doors.
6. Frog-lipped induction air inlet.
7. Re-shaped engine cowling with cowl flaps.
8. Stabilator gap brush seals.

They also tried out the installation of a Continental Tiara six-cylinder engine; I think it was 260HP as used in the Sierra application, though other versions were made through most of the 1970s (used in very limited applications). I don't think that the Tiaras ever made it beyond a TBO assignment of only 1,200 hours.

I have heard that there have been Beech speakers at the Wichita fly-ins, but I have not made it there yet. I haven't given up on the nose wheel fairing. I do think it would be far more effective if I could come up with a safe way to fair the axle strut too. Just haven't had time to pursue it further.

----- Original Message -----
From: g_v_jackson
Sent: Friday, September 02, 2005 3:27 PM
Subject: [musketeermail] Re: wheel fairings

--- "Mike Rellihan" wrote:
> ...
> The Beech leading fairing does not have the ideal front shape; it
> is too blunt.

Given my presumption that aeronautical engineers were involved in the
design, any thoughts as to why would such a design decision be made?

> The aft fairing should be tapered aft as far as is practical.
> The Beech main gear aft fairing is actually only about 2/3s as long
> as it should be, ...

This, I presume, was done to save weight.

> ... and is too abrupt where the flange is formed on the trailing
> edge.

Where was the aeronautical thinking in this decision?

> The overlapped fairings that were made for the flap brackets,
> during the experimentation by the Sierra engineering group, went
> almost to the trailing edge of the wing.

Flap hinge fairings are part of the bread and butter of Piper speed
mods. Again, a small weight penalty situation. Did they not find
them of sufficient performance/weight/cost benefit?

> An experimental aft fairing that I made for the retracted nose gear
> wound up a tad too wide for the wheel, and wasn't long enough. I
> was unable to tell any effect at all during its testing (meaning
> back to the drawing board).

I have wondered about this type of nose gear fairing myself,
especially when I see the pictures of the tire dragging through the
air!!! Did you give up on it, or will you have another try?

Thanks for the info Mike! I have really been impressed with the
attention to detail that Beech gave to the structure, so these
apparent aerodynamic oversights are surprising.

Fortunately, that BIG rear door is a major part of the reason that I
own a C24R and the RG is a plus on top of that, but, you'd think they
would have gone a bit further to maximize its efficiency.

By the by, the Piper owner forums often have surviving design team
members come and speak at their national meetings to talk about the
why of the early design decisions. Has such a thing ever happened at
a meeting of the Mice?


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